Electromagnetic switch



Oct. 12, 1948'. w. E. STILWELL, JR

ELECTROMAGNETIC SWITCH 2 Sheets-Sheet 1 Original Filed Feb. 8, 1941 K/7/4 4 N N.

. D LEEEEE SHE 35252 INVENTOR Will m E.5ri|we||,Jn BY 9 v m 1 Oct 194$ wSTILWELL, JR 2,450,924

' nwcwnopmnnnc swn'cu Original Filed Feb. 8, 1941 2 Shoots-Sheet 2 LowVOLTAGE SOURCE INVENTOR I .v f wanna ESTilWelLJr.

. BY 1;! ,i w ke HI TORNEY Patented a. 12, 1948 William E. Stilwell,Jr.,

to John Gincinnati, Ohio, B. Pierce Foundation, New York, N. Y.,

minor a corporation of New York Continuation of application semi No.February 8, 1941. This application 378,068, September 18, 1943, SerialNo. 502,924

This invention relates to electromagnetic switches, and particularly toself-enclosed .remotely controlled magnetically operated switches. Anobject of the present invention is .to provide a self-enclosed lowvoltage magnetically operated switch which is designed to make and breakelecly operated switch actuator element which is completely responsiveto momentary energization.

Still a further object of the invention is to provide a switch device01' the type hereinabove described wherein the high voltage circuitmaking and breaking stroke' is rapid and positive in action.

Another object of the invention is to provide a switch having the abovecharacteristics, which includes means for making-and breaking the highvoltage load circuit in one or more places.

Another object of the invention is to provide a low voltage magneticallyoperated switch-for high voltage load circuits wherein the low voltagemagnetic actuator elements are electrically shielded and insulated fromthe high voltage contact elemen-ts, and wherein the device as a whole iselectrically and mechanically shielded from harmful external forces anddisturbances.

Another object of the invention is to provide improved means foraccurately positioning and securing operating elements of the circuitbreaker within a housing.

Still a further object of the invention is to pro- 2 Claims. (Cl.175-337) means described herein and disclosed in the accompanyingdrawings. in which:

, vFig. 1 is a longitudinal sectional view of a switch linufacturedaccording to the present invention; Fig. 2 is a section taken on lines2-2 of Fig. 1;

Fig. 3 is a side elevation. partly in section showins the securement ofthe switch head to its supporting structure;

Fig. 4 is a sectional view, taken on lines 6-4 of Fig. l;

Fig. 5 is a plan view of the invention showing one method 01'installation in a standard electrical outlet box, with the low voltageswitch actuator element projecting through one side of the box; Fig. 5also illustrates schematically a wiring diagram for the controllingcircuit.

Fig. 6 is a side elevation of the switch and outlet box of Fig. 5, withthe outlet box portion in section; and

Fig. 7 is a plan view of the switch installed wholly within a standardelectrical outlet box.

Referring to the drawings the invention comprises a switch l0 and amagnetically operated actuator ll associated therewith. The switch isadapted for remote control, from any desired plurality of stations 8. asdiagrammatically shown in Fig. 5. The magnetic circuit of the actuatorII is preferably woun'd for low voltage operation, thus placing thewiring from. the control stations to the actuator not under therequirements imposed upon high voltage systems by national electricalcodes, and making possible substantial savings in weight and complexityof wiring and installation. The main switch contacts (usually highvoltage) of switch iii are entirely electrically isolated from themagnetic actuator ii. and therefore may be designed for any electricservice within code re-- quirements of installation.

The switch actuator ll includes a cylindrical body portion i2,preferably of steel or other magnetic material. A reduced diameter andfits into an aperture provided in an angle plate it; the housing may besecured to the angle plate I t by brazing or welding. A forwardlyextendingleg i5 of the angle plate has a slotted end through which ascrew or other fastening means may pass to secure the plate to the baseof a standard outlet box as shown in Figs. 5 and 6.

To the angle plate It is secured the base I 8 of the switch body l0,said base being of insulation material, and carrying the high voltageterminal plates I! and therewith associated fixed contacts J8 of themain switch circuit. Cooperating with said fixed contacts are movablecontacts 20, 20.

switch. and the small size to which the switch may be constructed, makespossible a variation in the manner in which, and in connection withwhich, the complete device may be installed in a standard electricoutlet box. Figs. 5 and 6 show the switch so arranged with respect to anoutlet box 24 that the high voltage part of switch ll is within the boxfor securement to the base plate thereof or through the base plate tothe wall studding, whereas the low voltage switch actuator II and all ofthe low voltage wiring associated therewith is outside of the box. Suchan arrangement is advantageous in an installation where the outlet boxserves as a junction or several high voltage leads. the connecting andtaping of which may take up a large portion of the volume of the box.The housing I2 of switch actuator H has an external diameter whichpermits it to be passed through one of the knock-out openings of thebox.

As shown in Fig. 7. the entire switch assembly may be included withinthe confines of the outlet box if it is desired to protect the switchfrom plastering or other ceiling or wall finish during the constructionof a building in which the system is used.

It is considered to be an important feature of the invention that it maybe completely within an outlet box or so disposed with respect theretothat only the high voltage portion of the apparatus is positioned withinthe box, to maintain the independence in the high and low voltagewiring.

The member 2! is guided in its movement within base it by diametricallateral extensions. see Fig. 4. Said member is secured to an end of abrass shaft 26, by means affording self-adjusta bility of the member, sothat the movable and fixed contacts .will engage despite slightirregularities in the positioning thereof.

To the opposite end of the shaft 26 there is secured an overthrow springor snap-acting member 21 held with its periphery in engagement with asloping shoulder 28 of the housing l2. Said spring is desirably asdescribed and claimed in my co-pending application Serial No. 441,382,filed May 1, 1942, which subsequently became abandoned, for Togglesprings.

The shaft 28 is guided in its longitudinal movement by passage throughthe aligned bores of two end stops or cores 30 and 3|, which receive theslidable shaft. The end stops are of steel or other magnetic materialand are suitably positioned within the housing 12; it will be noted thata shouldered end of stop 30 rests against an inner end wall of housingi2, and that the flanged head of end stop II abuts a shoulder 32provided within housing l2.

Disposed about the end stop ll is a solenoid coil 33, and about end stop3! is a solenoid coil 34; when the coils are energized selectivelythrough the wiring circuit (shown in dotted lines) the respective endstop of the energized 4 coil forms a pole of the magnetic system therebycreated. Between said coils is disposed a metal annular member II, being1 with the iron or steel housing i2, and positioned in the housing inengagement with a shoulder II formed therein. Said annular member 8|serves also to position the solenoid spools by the interfitting ofshoulders 31 thereon into a groove on the respective sides of theannular member.

Secured to the shaft 20 is a magnetically responsive armature 38 havingan outside diameter slightly less than the inner diameter of the annularmember 35 to avoid a frictional contact of the armature and the core. Itwill be noted that the ends of the armature are conical, correspondingto the conical depressions of the respective end stops 3' and ii.

The magnetic fiux created by the respective energized solenoids passesthrough and is confined within the high permeability structurecomprising the housing ii, the core members II (II), the annular memberll, and the armature 18, all of which are preferably of metals havinghigh magnetic permeability. This construction assures a powerful pull onthe armature 38 to insure immediate and strong response to the controlcircuit.

If desired, the positioning of the end stops within the housing is suchthat the permitted travel of the shaft 20 in either direction is lessthan the total extent of throw of the toggle spring 21 from one to theother of its positions of stability. In Fig. 1, showing the switch inopen circuit position, the armature it has abutted against the end stopll before the spring 21 has completed its full throw, whereupon saidspring yieldingly holds the armature in engagement with the end stop.This is advantageous in avoiding hllm when the magnetic actuator II isemployed with alternating current. Likewise the engagement of thearmature I! with end stop 30 occurs before the spring has fully thrownto its other position of equilibrium so that said spring exerts acontinuous pressure in the given direction. 'It will be understood thatprior to the engagement of the armature with the end stop II,- themovable and fixed contacts of the switch II have come into engagement.

The precise relationship of the travel of shaft 28 and the position ofend stops l0 and ll is established by means of the respective shouldersof the housing It, as previously described.

To maintain the annular member 38 and the end stop ii in engagement withthe respective shoulders of the housing l2, and also accurately toposition the spring 21, there is employed an insulating end cap orspider lll formed with a rim II and a plurality of spaced legs II, thelatter straddling the spoked portions of the spring 21 as shown in Fig.2. The ends of the legs I! rest upon the surface of'the end stop ll andhold the end stop in position against the shoulder 32, and,

through the intervening solenoid ll, holds annular member 35 against theshoulder 3'. spring 21 is confined by means of a washer 43,

against the rim ll of the spider II. The spider 40 therefore serves asmeans to maintain the various operating elements of the switch in properrelationship one with the other.

To confine the spider ll in its position, there may be employed ametallic cap 44, the rim of which rests upon the cap ll, and is held inposition by beading or fianging an end of the housing I! about thecircumference of the cap, as shown in Fig. 1.

The solenoid spools, the annular member, and

The

end stop 3| are suitably slotted to accommodate the wiring from thesolenoids 33 and 34; passages 45 through the leg portions of spider 48are channels through which the wires may be run.

Whereas I have described my invention by ref erence to specific formsthereof, it will be under-- stood that many changes and modificationsmay be made provided they do not depart'from the scope of the claims.

I claim: I

1. Electromagnetic means, comprising a magnetic shell formed with aplurality of concentric bores of successively smaller diameters, theline of demarcation between successive bores being of the nature ofangular shoulders, magnetic end stop means and an intermediate magneticannular member positioned within said shell by engagement with saidshoulders, an armature slidably positioned within said annular memberfor operation between said end stops, a snap spring operativelyassociated with said armature, and cap means disposed within said shelland bearing against said snap spring and said end stop means to maintainthe positioning thereof within said shell.

2. Switch actuator means, comprising a tubular casing, electromagneticcoremeans disposed within said casing, a-n armature mounted forreciprocal movement between said electromagnetic core means, a snapspring having a rim portion supported peripherally by said casing and aspoked center portion operatively associated with said armature formaintaining the armature resiliently at either of its extremes ofreciprocal movement, cap means having a rim engageable with the rim ofsaid snap spring to maintain the support thereof by said casing and legmeans straddling the spoked portion of said snap spring and engageablewith said electromagnetic core means to maintain the positioning thereofwithin the casing, and means for securing the cap means within saidcasing.

WILLIAM E. STILWELL, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES EATENTS Number Name Date 267,711 Peck et a1. Nov. 21, 1882519,662 Carpenter May 8, 1894 728,752 Naphthaly et al. May 18, 1903773,120 Christmas Oct. 25, 1904 773,122 Christmas Oct. 25, 1904 814,322Perkins Mar; 6, 1906 995,448 Achard Apr. 19, 1910 1,164,475 Croston Dec.14, 1915 1,275,766 Schoenwolf Aug. 13, 1918 1,434,637 Tuck Nov. 7, 19221,485,750 Wolfe et ai. Mar. 4, 1924 1,571,401 Erickson Feb. 2, 19281,733,085 Thomas Got. 22, 1929 1,861,046 Bower May 31, 1932 1,891,540Howard Dec. 20, 1932 1,891,541 Howard Dec. 20, 1932 1,983,740 Deary Dec.11, 1934 2,151,213 Kelley Mar. 21, 1939 2,174,868 Coffeen Oct. 3, 19392,258,586 Glassing Oct. 14, 1941 2,284,891 Hartig June 2, 1942 2,313,379Wood Mar. 9, 1948 2,360,666 Fish Oct. 17, 1944

